In-situ Synthesis of MoSi₂-Al₂O₃ Composites by Self-propagating High Temperature Synthesis

Abstract

MoSi₂-Al₂0₃ composites with 0-50 vol% Al₂0₃ were in-situ fabricate by self-propagating high temperature synthetic process. The compacts of the powder mixture of MoO₃, Al, Si and MoSi₂ were encapsulated in Pyrex tube and then HIP'ed at 1573K under pressure of 196MPa. Self-propagation synthesis reaction occurred during elevated temperature and pressure.
Relative density of HIP'ed samples decreased with increasing addition of MoSi₂ pre-alloyed powder to the starting powder mixture.
Vickers hardness and fracture toughness were performed to investigate the mechanical property of composites. Vickers hardness increased linearly with increasing volume fraction of Al₂O₃ tested. The indentation fracture toughness of 50 vol% Al₂O₃ composite was two times lager than that of monolithic MoSi₂.